R help - Aug 2004 - Post-hoc t-tests in 2-way repeated measure ANOVA

Hi all

I am running a 2-way repeated measure anova with 1 between-subjects 
factor (Group=treatment, control), and 1 within-subject factor (Time of 
measurement: time1, time2).  I extract the results of the anova with:

summary(aov(effect ~ Group*Time + Error=Subj/Time, data=mydata))

Now, this must be clearly a dumb question, but how can I quickly extract 
in R all the post-hoc t-tests for the simple main effects?

Also, while I am at it, how do I enter in the model a counfounding 
covariate (e.g., Age)?

And on a different matter, is there a way to receive interactive user 
input in an R script? Something like "Enter the name of  the factor: 
",
or even more simply "Press <Enter> to see the result of the next 
analysis"....

thanks in advance for any suggestions!

    giuseppe

-- 
------------------------
Giuseppe Pagnoni, Ph.D.
Dept. of Psychiatry and Behavioral Sciences
1639 Pierce Drive, Suite 4000
WMB Bldg., Atlanta, GA 30322, U.S.
phone: 404-712-8431
fax: 404-727-3233
e-mail: gpagnon at emory.edu

Hi all

I will repost this since it seems to me such a common problem and I 
couldn't find any solution in the mail list...

I am running a 2-way repeated measure anova with 1 between-subjects
factor (Group=treatment, control), and 1 within-subject factor (Time of
measurement: time1, time2).  I extract the results of the anova with:

summary(aov(effect ~ Group*Time + Error(Subj/Time), data=mydata))

following the notes of Jonathan Baron.

Now,is there a way in R to quickly extract all the post-hoc t-tests for 
the simple main effects, corrected of course for multiple comparisons?

Group1 at Time1 vs Group1 at Time2
Group2 at Time1 vs Group2 at Time2

Group1 at Time1 vs Group2 at Time1
Group1 at Time2 vs Group2 at Time2



Also, how can I enter in the model formula a counfounding
covariate (e.g., Age)?

thanks in advance for any suggestions!

    giuseppe

-- 
------------------------
Giuseppe Pagnoni, Ph.D.
Dept. of Psychiatry and Behavioral Sciences
1639 Pierce Drive, Suite 4000
WMB Bldg., Atlanta, GA 30322, U.S.
phone: 404-712-8431
fax: 404-727-3233
e-mail: gpagnon at emory.edu